System of plural solution mining cavities communicating with a single station



P 1967 J. B. DAHMS ETAL 3,339,979

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SYSTEM OF PLURAL SOLUTION MINING CAVITIES COMMUNICATING WITH A SINGLE STATION Filed May 17, 1965 ROCK- Na.C|

DEPOSIT xcl RICH osPosn mcl' ne osw INVENTORS JAMES B.OAHM9 1 FIG 2 BYRON R EDMONDS ATTORNEYS P 5, 1967 J. B. DAHMS ETAL 3,339,979

SYSTEM OF PLURAL SOLUTION MINING CAVITIES COMMUNICATING WITH A SINGLE STATION 7 Filed May 17, 1965 2 Sheets-Sheet 2 PRODUCT MINERALS INVENTORS JAMES B. DAHMS anecw P. eomozvos ATTORNEYS United States Patent Ofilice 3,339,979 SYSTEM OF PLURAL SOLUTION MINING CAVITIES COMMUNICATING WITH A SINGLE STATION James Bowen Dahms, New Martinsville, W. Va., and

Byron Priestly Edmonds, Regina, Saskatchewan, Canada, assignors to Kalium Chemicals Limited, Regina, Saskatchewan, Canada, a corporation of Canada Filed May 17, 1965, Ser. No. 456,271 18 Claims. (Cl. 299-4) ABSTRACT OF THE DISCLOSURE A plurality of solution mining cavities is operated from a single station. Fluid-carrying conduits are provided from the station to remote extraction sites. Solvent is fed to the sites to extract minerals. Extracted minerals are withdrawn from the sites to the station.

This invention relates to mining a soluble. It more particularly relates to providing a system of conduits to a plurality of cavities to facilitate forwarding solvent and recovering enriched effluent from a plurality of solution mining cavities located at remote locations within a product mineral deposit.

In a typical solution mining operation, a plurality of bore holes are established through a plurality of strata of varying composition to a lower deposit of product minerals. By product mineral is meant a mineral which it is commercially desirable-to extract. These minerals are extractable with suitable solvents, typically with aqueous media including mineral acids, steam, salt solutions, e.g., solutions of NaCl and/or KC], substantially pure water, etc. The bore holes are normally fitted with suitable conduits in the form of casings or concentric tubes. The solvent is introduced to the product deposit through one of these conduits to extract product minerals. Solvent laden with product minerals is withdrawn from the deposit through another conduit thereby forming a cavity in the mineable (product) deposit.

It is usually desirable to locate solution mining cavities spaced within the product deposit. Several such cavities are operated at commercial levels simultaneously. Usually a cavity must attain a certain size before it is capable of producing commercial products at acceptable rates. After a period of operation, the productivity of a cavity typically falls off. Thus, it is desirable to have a plurality of cavities at various stages of development in a product deposit. In this fashion, when a solution mining cavity has developed beyond its optimum size, other cavities are developed to sufl'icient size to produce commercially required quantities of product minerals. The amount of product mineral which can be recovered per hour from a particular solution mining cavity is limited. For this reason, it is usually necessary to develop and operate a plurality of cavities simultaneously to provide suflicient eflluent to the recovery operation.

,Heretofore, it has been common practice to locate in the vicinity of each solution mining cavity an individual pumping, valve, or control station. This practice necessitates providing a network of above ground conduits to provide solvent to these individual stations. A similar network of conduits is needed to forward efliuent from the cavities through the individual stations to a reservoir or directly to the recovery operation. Providing these above ground conduits requires extensive capital expenditure and time-consuming construction. The productivity of the soil is destroyed at a number of points by the installation of these service pipe lines. In addition, provision must be 3,339,979 Patented Sept. 5, 1967 made to protect the above ground lines from the effects of weather, particularly to guard against freezing in cold climates. Operation and maintenance of a plurality of individual stations consumes time and labor.

According to the instant invention, an improved system is provided whereby solvent feed and eflluent recovery from a plurality of cavities are effected through a single control station thereby eliminating much of the capital, maintenance and labor costs heretofore expended by the solution mining industry. Thus, it is now economically feasible to construct a substantial building to house the control operations area.

In the practice of this invention, a single control or conduit station is provided from which a plurality of conduits are extended to a plurality of extraction sites within a product mineral deposit. The extraction sites are remote from each other. The conduits preferably extend from the station to the extraction sites along the shortest possible route, that is, they are drilled at an angle with a substantial horizontal component such that the conduit lies in an essentially straight line from the conduit station to the extraction site.

The conduits may take the form of concentric pipes or tubes such that a smaller conduit is disposed concentrically Within a larger conduit to provide a plurality of passageways in a single bore hole. It is usually preferred to provide a plurality of spaced conduits to a particular extraction site. Operating separated conduits as influent and efiluent conduits respectively, the descending feed is kept substantially out of thermal contact, i.e., direct heat transfer relationship with the ascending efliuent thereby avoiding loss of heat by the feed to the efiluent. While it is possible to insulate concentric pipes to minimize heat transfer between fluids carried therein, it is preferred to space the influent conduit from the effluent conduit. In this fashion, the conduits are physically separated by naturally occurring materials.

According to a preferred embodiment of this invention, a pair of bore holes is initially provided to an extraction site. Each bore hole is provided with a concentric system of conduits. A small cavity is then developed at the terminus of each bore hole by providing solvent to the extraction site through an internal conduit and withdrawing effluent from the extraction site through the annulus between this internal conduit and a larger concentric conduit. The two cavities are developed until they communicate. After the cavities communicate, the internal conduits are removed. The larger or outer conduits are then utilized to provide solvent to and withdraw efiluent from the re-v sulting cavity.

Although this invention is generally applicable to any solution mining operation, it finds particular application in solution mining NaCl-cont-aining deposits. The invention will be more readily understood with reference to the accompanying drawings which illustrate operation of the invention in a KCl-rich, NaCl deposit from which it is desired to recover the KCl values. FIGURE 1 of the drawings illustrates in plan view a field of solution mining cavities with a centrally disposed conduit station. 'FIGURE 2 shows a similar arrangement in section. FIG- URE 3 illustrates a preferred embodiment wherein the conduits enter the extraction site in a substantially vertical direction.

Referring to the drawings, in the practice of this in-. vention, a control station 1 is positioned in the vicinity of a plurality of extraction sites 2, preferably the station is directly above an extraction site. Pairs of bore holes, designated 3 and 4 in the drawings, are then provided by well-known techniques to a plurality of remote cavity sites (extraction sites) located within the product mineral deposit. Cavities 5 are then established at a plurality of 3 these extraction sites. The cavities may be developed by any recognized technique, for example, by fracturing between the bore holes, by extraction through concentric pipe arrangements or any other convenient technique. Preferably each cavity is brought into communication with a pair of conduits such as pipes 3 and 4.

Once cavities 5 have been developed, the extraction of the deposit proceeds by forwarding solvent from the centrally located control station 1 through influent conduits 3 to extract the deposit. Enriched efiluent is withdrawn from the cavities through conduits 4 and recovered at station 1. The effluent is then forwarded to a reservoir 01' recovery operation above ground. Of course, it is within contemplation that each of the cavities be operated independently, that is, one or more of the cavities can be operated while the remainder of the cavities are held in reserve or any number of the cavities may be operated simultaneously. The control station ideally contains a system of valves allowing an operator to control the amount of flow into or out of any chosen cavity.

In the preferred embodiment of this invention, all of the conduits are maintained substantially beneath the surface of the earth, thereby avoiding the necessity for elaborate insulating precautions to avoid freezing or weathering of above ground conduits. The cavities contemplated by this invention are otherwise operated in accordance with recognized solution mining practices.

FIGURE 3 illustrates a preferred embodiment of this invention. It has been found desirable to orient conduits having substantial horizontal components along their length so that they enter the product deposit at a substantially vertical angle. During the development and/or operation of a solution mining cavity, it is frequently necessary or desirable to forward various measuring or mining instruments through a conduit to a solution mining cavity. On entry of the instrument into the cavity, it is frequently desired to orient the instrument in controlled fashion to a desired direction or range of directions. Orientation of the instrument toward cavity walls, for example, is greatly facilitated when the instrument enters the cavity in a substantially vertical direction with relatively minor or no horizontal component. During the operation of a cavity, the roof level is usually raised until it ultimately reaches 'at least the top interface of the product mineral deposit. It is thus preferable to initiate the vertical orientation of the conduits at a level above the product mineral deposit to allow for normal vertical expansion of the cavity.

Although the invention has been described with particular reference to details of certain specific embodiments thereof, it is not intended to thereby limit the scope of the invention except insofar as these details are recited in the appended claims.

We claim:

1. A solution mining system comprising a station at the surface of the earth and communicating with said station a plurality of sets of fluid-carrying conduits of which sets no more than one extends in a substantially vertical direction to an extraction site in a subterranean extractable deposit and the remainder extend from said station in directions with substantial horizontal components to extraction sites in said deposit but laterally remote from said station.

2. The system of claim 1 wherein the station is centrally located with respect to the extraction sites.

3. The system of claim 1 wherein the conduits traverse essentially the shortest distance between the station and the extraction sites.

4. The system of claim 1 wherein all of the conduits are maintained substantially completely beneath the surface of the earth and the directional orientation of the conduits with horizontal directional components is altered to essential-1y vertical at a point near and above a product mineral stratum.

5. The system of claim 1 wherein each set of conduits comprises a pair of conduits arranged so that solvents may be fed from the station through one conduit of said pair to an extraction site while effiuent is withdrawn from said extraction site through the other conduit of said pair.

6. The system of claim 5 wherein the conduits are substantially out of heat transfer relationship with each other.

7. The system of claim 6 wherein the conduits are physically separated by naturally occurring materials.

-8. A solution mining system comprising a station at the surface of the earth and communicating with said station a plurality of sets of fluid-carrying conduits of which sets no more than one extends in a substantially vertical direction to an extraction site located in a subterranean NaCl-containing deposit and the remainder extend from said station in directions with substantial horizontal components to extraction sites in said subterranean NaCl-containing deposit but laterally remote from said station.

9. The solution mining system of claim 8 adapted for solution mining KCl in which the sets of fluid-carrying conduits communicate with extraction sites in a subterranean deposit containing NaCl and rich in KCl.

10. The system of claim 8 wherein the station is centrally located with respect to the extraction sites.

11. The system of claim 8 wherein the conduits traverse essentially the shortest distance between the station and the extraction sites.

12. The system of claim 8 wherein all the conduits are maintained substantially completely beneath the surface of the earth and the directional orientation of conduits with horizontal directional components is altered to essentially vertical at a point near and above the KCl-rich stratum.

13. The system of claim 8 wherein each set of conduits comprises a pair of conduits arranged so that aqueous solvent may be fed from the station through one of the conduits of said pair to an extraction site while an aqueous solution of KC-l is withdrawn from said extraction site through the other conduit of said pair.

14. The system of claim 13 wherein the conduits are substantially out of heat transfer relationship.

15. The system of claim 14 wherein the conduits are physically separated by naturally occurring materials.

16. A solution mining system comprising a station at the surface of the earth and communicating with said station a plurality of sets of fluid-carrying conduits, each of said sets extending downwardly in directions with substantial horizontal components to extraction sites laterally remote from said station in a subterranean extractable deposit.

17. The system of claim 16 wherein the extraction sites are located in a subterranean NaCl-containing deposit.

18. The system of claim 17 wherein the NaCl-containing deposit is rich in KCl.

References Cited UNITED STATES PATENTS 823,749 6/ 1906 Wanner. 2,682,396 6/1954 Haworth 2995 X 2,966,346 12/ 1960 Huitt et al. 299-4 2,979,317 4/1961 Bays 299-4 OTHER REFERENCES Russia Gang Drills, Oil and Gas Journal, Dec. 10, 1956, page 105.

E NE T R, 'PURSER, Primary x r.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,339,979 September 5, 1967 James Bowen Dahms et al It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 4, lines 27, 29, 32 and 38, for the claim reference numerals "8", each occurrence, read 9 Signed and sealed this 5th day of November 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. A SOLUTION MINING SYSTEM COMPRISING A STATION AT THE SURFACE OF THE EARTH AND COMMUNICATING WITH SAID STATION A PLURALITY OF SETS OF FLUID-CARRYING CONDUITS OF WHICH SETS NO MORE THAN ONE EXTENDS IN A SUBSTANTIALLY VERTICAL DIRECTION TO AN EXTRACTION SITE IN A SUBTERRANEAN EXTRACTABLE DEPOSIT AND THE REMAINDER EXTEND FROM SAID STATION IN DIRECTIONS WITH SUBSTANTIAL HORIZONTAL COMPONENTS TO EXTRACTION SITES IN SAID DEPOSIT BUT LATERALLY REMOTE FROM SAID STATION. 